Process for treating spirit soluble nigrosines



Patented Jan. 22, 1935 N I'T ED new O FFlC-"E w New-York j I No Drawing; .iApplication' Malrch 28,.tl'93 l,'

. Serial No..5 26,144

. lziclaims. w (Cl'.1260'i;-'29) '1 This invention relates 'to. a procession-treating spirit soluble nigrosines, and-;to\ the ..-product obtainedrthereby.

:jl'he: ,hydrochloridesyt of t the. coloring matters g produced-Joy the action of. nitro :compounds. of

the aromatic series, for example, nitrobenzene. or nitrophenol, on-:arylamines,. .in the; presence, or absence ofi a catalyst,-such-as ,iron. chlorides are known; as: spirit soluble nigrosines or spirits nigrosines. s'lhese coloring-matters are, soluble alcohol, and are precipitated ifrom their: alcoholic solution: byadditionof. alkali thereto. H

.One of the. objects :of .the present -invention,-is the-production of a a spirit nigrosine; which has a greatensolubility .in; alcohol. Apfurther' .object is .the production. of aspirit nigrosine which: has a brighter shade. Still another object of ,the invention iS'i theiproductioneofi spirit-nigrosine in a form: which is readily. separated from-its- -aqueous= suspensions :by-filtration. .+A-;rfurther ob-ject is: the-production of" a :spirit-nigrosine -whichs-is suitablePfor use in coloring-molding. resins,--.rand which, when 'so-;used,=.'will not- 1 cause; pitting-1 of thermold E'Ihese'rand othen objects of: the invention are--accomplished-by the present invention-.as =.wi 1l rbec'ome?readily=apparent :upomconsideration, 50f athe: rfollowing descriptionvoj .the invention; 7 r I 1 .eAccording-to the present invention,- spirit. soluble :nigrosines prepared the ;usual manner as above described are treated with-tan: acid removing r medium; more .-particularly. an alkali, preferably: a-small quantity of. an: alkali. :The' ,coloring matters, after such treatment, -become --less gelatinous insaqueoussuspensions and are more easyvto :filtenandswa'sh. ,=They. aretalso :more solublein alcohol which; property renders. ithem particularly :usefulfor coloring. lacquers, spirit varnishes; etc.,- andiresinseqg zof {the -!.Bakelitef, fGlyptal, urea-formaldehyde ,type, "eta, andwwhenemployed in coloring.-v molding: resins they have 1it,tle: or.;'no tendency-.to,pit;=thermold. The rwcoloring matters, aftertreatment with alkali .accordingxtotthei: present invention havei a redder appearance when-dry; as vwell as; inr. alcohol "solution, .than -.-'colori11g matters not vso treated. .ex-Inwiew of :the' action of-alkalis orralcoholic solutions; of .the spirit soluble: nigrosines, itrwas not tO lbe': expected that .treatmentiofzthe colorin'gzmatten with 21,-: small quantity bf. alkali would render the samemore soluble; .fFrefierably, .the treatment of the coloring matter withalkali' is carried-out in aqueous media. It may he' -performed during the. processof-manufacture' of the: coloring matt'en or it: may be carried outronithe finished: coloring matterwith substantially equal results. The amount ,of .-al.- kalLadded. is,. .preferably--that which 7 is suflicient to; giveaspiritsolublemigrosine which is neutral to Congomedtest;paper. 1

carrying out :the present 1 invention according rte-the preferred method? of procedure, a crudeqspiriti soluble nigrosine melt, for example, as prepared by heating aniline, hydrochloric acid, .-nitrobenzene 9 and. iron chloride toa, temperature-of.- about .-C .,-:iS drowned with agitation :in dilute, hydrochloric acid to reduce the melt taya granularamass, and after permitting the solidsrto settle, thersupernatant liquid .is .decantedwofif. 'I-fheresidual-rmass of coloring -matten is iwashed'z-by-i agitating :the same. with .water, permitting the coloring .matter -.t0: settle and de-- cantingmfi =the asupernatent liquid. 'l his washingrmaysbe repeated-one onmore times. Finally, the residue of coloring matter is agitated with watera and.while,..the resulting slurry is agitated,

thereeisegradually radded alkali, preferably an aqueousz solution ..ofcaustic soda, until the ;re,- sultingssslurry showsa faintalkaline-reaction to indicators. Althoughi thisalkalinityqof theliquid does: .not; persist, e.,-r;it disappears after the liquid stands foria- -few-minutes, so' that a test onthe liquidmade: a' few-minutes later'will notwshow .-an.-' alkaline reaction, the quantity oi alkali :is'; nevertheless 'sufiicient-ii-it produces .just a -faint-- alkaline: reaction. The coloring matter is theni allowed. -'to: settle, and thesupernatant liquid:qis -decantederoff. The .dyestuff "lS then filtered,- -washed with -=wateron :the filter, dried and ground. I r

21inapplying theinvention tothe treatment ofthea-finished spirit -nigrosinev the finely divided coloring matter is suspended in-water,- and to the well vagitated; suspension is added .a solutioncf alkali: -,until% the suspension shows a faint alkaline (11782101331011 to brilliant yellow :test paper. Upon} standing for, about five minutes the alk'alinity "pfithex-suspension will have disappeared. Howeven-xthe suspension I will not; show an I acid reaction rtoqGongo-red:test paper. .1Theainvention @will i beillustrated .by the following example.

.;A.-;Nigrosinec.meZt.--Anj:iron. liquor is preparediaby adding 1400 :pounds: of-iron borings orhtwrningssgra'dually.:to 7500.:pounds of; 20 -B. hydrochloric:acid,::heating thermass to boiling to dissolve:.:-the r.iron,&.and-.thena'allowing 1 insoluble matterzinnthe liquorxto settle. 1.1595 :POUIldSzOf aniline; oil,1'465 pounds of 2 0 BKhYdIOChIQIiC acid andlflfiipounds of .the iron are now gradually added, at the sametime raising the temperature of the charge in the kettle to about C. Any water formed during the reaction will pass through thereflux condenser, which is maintained at about the boiling point of water, in the form of steam, while the greater part of the oils will be condensed andreturned.

1;,The process which comprises treating an aqueous suspension of spirit nigrosine having to the reaction. The temperature is thengincreased to about C. where it is held for about 12 hours more or less, or until the reaction 7 a is completed, as indicated when the reaction mass no longer contains an appreciable amount of nitrobenzene. r i

The melt is then blown into a'vatcontaining about 8,000 pounds watermixed with about 800 pounds 20 B. hydrochloric acid while the liquid in the vat is agitated. When the melt has been added, the contents of the vatare heated to boiling for about one hour, and is then tested for acidity with Congo red-test" paper. If no acidity is shown in this test more hydrochloric acid is added until the -acid'reaction to Congo red persists. 'I'hecontents '0f 'the vat arethen allowed to settle for several hours, and the supernatant liquid is decanted off. To theremaining color in the vat is-added about 8,000 pounds water, and the contentsof the vat are heated to boiling with agitation for about one hour. The batch is then allowed to settle again for several hours and the supernatant liquid is decanted ofl.

B.Treatment with aZkaZi.To the color in the vat is now added about 2,000 pounds water, and the contents of the vat are heated to about 40 C.,- with agitatioiifl Aqueous causticsoda' is gradually added until the liquid in the vat shows a faintly alkaline reaction to brilliant yellow test paper, about 30 pounds of 47 B. aqueous caustic'soda being required.- This alkaline"r'e action' ofthe liquid does not persist, for a test taken a few minutes later with brilliant yellow test paper will not show an alkalinev reaction, neither will a test with Congo red test paper show an acid'reaction. The contents" of the vat then are dropped to a filter press where it is filtered, washed with water, and blown dry. The color when dried and ground is a reddish black powder. It is soluble in alcohol, and practically insolublein'water'. I

It will be understood that the invention is not limited to the details "of manufacture of the nigrosine hydrochloride as above described. The proportion of ingredients in the melt may-be varied; the time of heating and otherdetails of operation may be varied, as well known in the art, to produce various'shades of nigrosine hydrochloride without departing from the present invention. r

The exact proportion of alkali to be added to the spirit soluble nigrosines cannotbe definitely stated in all cases. 'To some extent it will depend on the thoroughness of the prior washings to remove the hydrochloric acid. *Ingeneral, it may be stated thatthe quantity of alkali employed isJsuch as will produce a faintly alkaline reaction to brilliant'yellow test paper. A slightly greater quantity of alkali, for example, just sufiicient to produce a permanent alkaline reaction, tends to reduce the solubility of the coloring matter in alcohol but does not render it unfit for use incoloring molding resinssinceit still eliminates pitting of themolds. The use of such quantity of alkali also still renders the coloring matter less gelatinous and permits the coloring matter to be more easily filtered.

In 'place' of caustic soda employed in the above example, other compounds which are acid binding agents may be used, such as lime, potash,

. soda ash; ammonia, etc., with substantially equal resul s."

Having described my invention what I claim as, nevi andwish to secure by Letters Patent is:

3. The process" which comprises treating an aqueous suspensionof spirit nigrosine having an acid reaction to Congo red test paper with alkaliin an amount adapted to render the suspension faintly alkaline in reaction.

4. The process which comprises treating an aqueous suspension of spirit nigrosine having an acid reaction to Congo red test paper with a solution of alkali in an amount adapted to render the suspension faintly alkaline in reaction. i

5. The process which comprises treating an aqueous suspension of spirit nigrosine having anacid reaction to Congo red test paper with a solutionof caustic soda in an amount adapted to render the suspension faintly alkaline in reaction' to brilliant yellow test paper.

6. In the production of spirit soluble nigrosine by reacting a intro-compound ofthe aromatic series with the hydrochloride of an arylamine, Whereby a'spirit soluble nigrosine having an acid reaction to Congo red test paper is produced, the improvement which comprises treating said spirit soluble nigrosine in aqueous suspension with an alkali in an amount sufficient to eliminate the acid reaction to Congo red test paper. 7 '7. In the production of spirit soluble nigrosine by reacting a nitro-compound of the aromatic series with the hydrochloride of an arylamine in the presence of iron chloride, whereby a. spirit soluble nigrosine having an acid reaction to Congo red test paper is produced, the improvement which comprises treating said spirit soluble nigrosine in aqueous suspension with a small quantity of alkali, whereby the acid reaction to Congo-red test paper is eliminated.

8. The process which comprises reacting a nitrocompound of the aromatic series with the hydrochloride of an arylamine for the production-of spirit nigrosine, drowning the spirit nigrosine in water, washing out excess hydrochloric acid, and treating a suspension of the spiritnigrosine with a small quantity of alkali sufiicient to show a faint alkaline reaction to brilliant yellow. test paper.

9. The-process .which comprises treating spirit soluble. nigrosine having an acid reaction to Congo, red testpaper witha small amount of an inorganic acid-binding agent selected from the group consisting of, caustic soda, lime, potash, soda. ash and ammonia, in an aqueous medium, whereby a product neutral to Congo red test paper is obtained.

10. The process which comprises treating spirit soluble nigrosine having an acid reaction to Congo red test paper with an alkali in an amount substantially just sufficient to give a resulting product neutral to Congo red test pa v 11. A spirit soluble nigrosine obtainable by the interaction of a nitrocompound of the aromatic series with the hydrochloride of an arylamine and which, when dry and ground, forms a reddish-black powder readily soluble in alcohol, insoluble in water, and which in aqueous suspension is neutral to Congo red test paper.

12. A spirit soluble nigrosine obtainable by the interaction of a nitro benzene with aniline hy drochloride and which is readily soluble in alcohol, insoluble in water, and when dry and ground appears as a reddish-black powder which forms a suspension in water that is new 10 tral to Congo red test paper.

SPENCER C. KIMMEL. 

